I also recommend the Lyman sight as it is a direct bolt stop replacement and requires no modifications to the rifle. Also the rifle can be returned to it's original state with little effort by reinstalling the original bolt stop. All this is done without drilling, tapping or modifying the stock.

You may think that the aperture bridge that is over the bolt will interfere with working the bolt. Not so as the aperture bridge is on a pivot so that when you pull the bolt back the bolt handle pushes the aperture bridge out of the way and then the aperture bridge will return to the proper position when the bolt is closed.

The only problem will be in locating a Lyman sight but patience and perseverance will prevail.

As an aside you will find that the Mannlicher Schoenauer rifle has such a slick action that if you open the bolt, hold the rifle level, hold the trigger down and then turn the rifle 45 degrees, muzzle down, the bolt will slide forward and down into the closed position. The only other rifle I know of that will do this the Gewehr 88 and the Gew. 88 sporting rifle derivatives.

You, Sir, have a wonderful rifle!

Vlad